Bi-directional d.c./d.c. converter compatible with an inverter bridge

Apparatus for directly coupling an inverter and a converter by connecting an elevator inverter, having a power stage which includes a d.c. circuit, to a storage battery having a battery voltage lower than the voltage in said d.c. circuit, said apparatus comprising:

• means for storing energy;
• first voltage matching means for causing said battery voltage to equal the voltage in said d.c. circuit when power is flowing from said storage battery to said d.c. circuit;
• said first voltage matching means comprising first semiconductor switch means for charging said energy storing means and first diode means for discharging energy from said energy storing means to said d.c. circuit;
• and
• second voltage matching means for causing the voltage of said d.c. circuit to equal said battery voltage when power is flowing from said d.c. circuit to said storage battery means;
• said second voltage matching means comprising second semiconductor switch means for charging said energy storing means and second diode means for discharging energy from said energy storing means to said storage battery means.

A method of connecting a storage battery to a d.c. circuit in a power stage of an elevator inverter, without using isolation diodes, pull up resistors or pull down resistors, the voltage in said d.c. circuit being higher than the battery voltage, and power flowing bidirectionally from the storage battery to the d.c. circuit and vice versa which method includes the steps of:

• employing a first semiconductor switch and a first diode to cause the battery voltage to at least substantially equal the voltage in the d.c. circuit when power is flowing from the storage battery to the d.c. circuit;
• said first transistor being employed to charge an energy store and said first diode being employed to discharge energy from said energy store to said d.c. circuit;
• and
• employing a second semiconductor switch and a second diode to cause the voltage of the d.c. circuit to at least substantially equal the battery voltage when power is flowing from the d.c. circuit to the storage battery;
• said second transistor being employed to charge said energy store and said second diode being employed to discharge energy from said energy store to said storage battery.

Apparatus for connecting an elevator inverter, having a power stage which includes a d.c. circuit, to a storage battery having a battery voltage lower than the voltage in said d.c. circuit, said apparatus not including isolation diodes, pull up resistors or pull down resistors, but rather comprising:

• means for storing energy;
• first voltage matching means for causing said battery voltage to equal the voltage in said d.c. circuit when power is flowing from said storage battery to said d.c. circuit;
• said first voltage matching means comprising first semiconductor switch means for charging said energy storing means and first diode means for discharging energy from said energy storing means to said d.c. circuit;
• and
• second voltage matching means for causing the voltage of said d.c. circuit to equal said battery voltage when power is flowing from said d.c. circuit to said storage battery means;
• said second voltage matching means comprising second semiconductor switch means for charging said energy storing means and second diode means for discharging energy from said energy storing means to said storage battery means.

A method of connecting a storage battery to a d.c. circuit in a power stage of an elevator inverter, by directly coupling said inverter and a converter without using isolation diodes, pull up resistors or pull down resistors, without using isolation diodes, pull up resistors or pull down resistors, the voltage in said d.c. circuit being higher than the battery voltage, and power flowing bidirectionally from the storage battery to the d.c. circuit and vice versa which method includes the steps of:

• employing a first semiconductor switch and a first diode to cause the battery voltage to at least substantially equal the voltage in the d.c. circuit when power is flowing from the storage battery to the d.c. circuit;
• said first transistor being employed to charge an energy store and said first diode being employed to discharge energy from said energy store to said d.c. circuit;
• and
• employing a second semiconductor switch and a second diode to cause the voltage of the d.c. circuit to at least substantially equal the battery voltage when power is flowing from the d.c. circuit to the storage battery;
• said second transistor being employed to charge said energy store and said second diode being employed to discharge energy from said energy store to said storage battery.

Apparatus for directly coupling an inverter and a converter by connecting an elevator inverter, having a power stage which includes a d.c. circuit, to a storage battery having a battery voltage lower than the voltage in said d.c. circuit, said apparatus not including isolation diodes, pull up resistors or pull down resistors, but rather comprising:

• means for storing energy;
• first voltage matching means for causing said battery voltage to equal the voltage in said d.c. circuit when power is flowing from said storage battery to said d.c. circuit;
• said first voltage matching means comprising first semiconductor switch means for charging said energy storing means and first diode means for discharging energy from said energy storing means to said d.c. circuit;
• and
• second voltage matching means for causing the voltage of said d.c. circuit to equal said battery voltage when power is flowing from said d.c. circuit to said storage battery means;
• said second voltage matching means comprising second semiconductor switch means for charging said energy storing means and second diode means for discharging energy from said energy storing means to said storage battery means.

A method of connecting a storage battery to a d.c. circuit in a power stage of an elevator inverter, the voltage in said d.c. circuit being higher than the battery voltage, and power flowing bidirectionally from the storage battery to the d.c. circuit and vice versa which method includes the steps of:

• employing a first semiconductor switch and a first diode to cause the battery voltage to at least substantially equal the voltage in the d.c. circuit when power is flowing from the storage battery to the d.c. circuit;
• said first transistor being employed to charge an inductance as an energy store and said first diode being employed to discharge energy from said energy store to said d.c. circuit;
• employing a second semiconductor switch and a second diode to cause the voltage of the d.c. circuit to at least substantially equal the battery voltage when power is flowing from the d.c. circuit to the storage battery;
• and
• turning on said first semiconductor switch, which is conductive during the time when power is flowing from said storage battery to said d.c. circuit, when the voltage in said d.c. circuit is lower than a reference value;
• said second transistor being employed to charge said energy store and said second diode being employed to discharge energy from said energy store to said storage battery.

Apparatus for connecting an elevator inverter, having a power stage which includes a d.c. circuit, to a storage battery having a battery voltage lower than the voltage in said d.c. circuit, said apparatus comprising:

• an inductance as a means for storing energy;
• first voltage matching means for causing said battery voltage to equal the voltage in said d.c. circuit when power is flowing from said storage battery to said d.c. circuit;
• said first voltage matching means comprising first semiconductor switch means for charging said energy storing means and first diode means for discharging energy from said energy storing means to said d.c. circuit;
• second voltage matching means for causing the voltage of said d.c. circuit to equal said battery voltage when power is flowing from said d.c. circuit to said storage battery means;
• and
• said second voltage matching means comprising second semiconductor switch means for charging said energy storing means and second diode means for discharging energy from said energy storing means to said storage battery means;
• including control unit means for providing control signals for turning on said first semiconductor switch, which is conductive when power is flowing from said storage battery to said d.c. circuit, when the voltage in said d.c. circuit is lower than a reference value.