# US 4,393,316 A · Transistor drive circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,393,316 A - Document ID: US4393316A - Status: Granted - Kind: A - Application number: 06/242,603 - Filed: 1981-03-11 - Granted: 1983-07-12 - Earliest claimed: 1981-03-11 - Assignees: Reliance Electric Company - Inventors: Harold J. Brown - Web page: https://patentgrep.com/patent/US4393316A ## CPC - H03K 17/04126: {in bipolar transistor switches} - H03K 17/601: {using transformer coupling (H03K17/61 takes precedence)} - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A drive current circuit for a switching power transistor which allows the controlled turn off of the transistor without affecting transistor turn on. The drive transformer has two cores one of which follows a linear magnetization characteristic and the other of which has a relatively high permeability. The input and output windings of the drive transformer are wound on both cores. A turn off winding is also included which is wound only on the high permeability core. A source of turn off charge is directly coupled to the transistor. Shorting of the turn off winding initiates the controlled turn off of the transistor. ## Claims ### Claim 1 A bipolar transistor drive and control circuit comprising: (a) a DC charge means directly coupled to said transistor for providing a source of charge for turn off of said transistor; (b) a transformer having both a high permeability magnetic core and a low permeability linear magnetic core said transformer also having input and output drive current means said input drive means receiving a drive current signal and said output drive means being connected to both said charge means and said transistor; and (c) turn off control winding means acting only on said high permeability core. ### Claim 2 (depends on 1) The circuit of claim 1 wherein said DC charge means includes charge storage means. ### Claim 3 (depends on 1) The circuit of claim 1 including means connected to said turn off control winding means for shorting said winding means at a predetermined time. ### Claim 4 (depends on 1) The circuit of claim 1 wherein a clamping circuit means is connected across said output drive current means. ### Claim 5 (depends on 4) The circuit of claim 4 wherein said DC charge means includes charge storage means. ### Claim 6 (depends on 5) The circuit of claim 5 wherein said DC charge means further includes a voltage reference means in parallel with said charge storage means. ### Claim 7 (depends on 6) The circuit of claim 6 wherein said charge storage means is a capacitor and said voltage reference means is a zener diode. ### Claim 8 (depends on 1) The circuit of claim 1 wherein said transformer further includes regenerative current means connected to said transistor. ### Claim 9 A drive and control circuit for a bipolar transistor comprising: (a) means directly coupled to said transistor for providing a source of charge for turn off of said transistor said means having a substantially constant voltage at least during said turn off; and (b) a drive transformer having both a low permeability linear magnetic core, and a high permeability magnetic core said transformer including: (i) an input winding for receiving a drive current of alternating polarity; (ii) an output winding connected between said source and said transistor; and (iii) a turn off winding wound only on said high permeability core. ### Claim 10 (depends on 9) The circuit of claim 9 wherein said charge source means includes means for storing said charge. ### Claim 11 (depends on 9) The circuit of claim 9 including means connected to said turn off winding for shorting said winding at a predetermined time. ### Claim 12 (depends on 9) The circuit of claim 9 wherein a clamping circuit means is connected across said output winding. ### Claim 13 (depends on 12) The circuit of claim 12 wherein said charge source means includes means for storing said charge. ### Claim 14 (depends on 13) The circuit of claim 13 wherein said charge source means further includes a voltage reference means in parallel with said charge storage means. ### Claim 15 (depends on 9) The circuit of claim 9 wherein said transformer further includes a proportional drive winding. ### Claim 16 A drive and control circuit for a bipolar transistor having a base, an emitter and a collector, said circuit comprising: (a) a reverse DC charge means having positive and negative terminals said positive terminal being directly connected to said emitter; and (b) a transformer having both a high permeability magnetic core and a low permeability linear magnetic core said transformer including: (i) input means for receiving a drive current of alternating polarity; (ii) output means connected between said base and said charge means negative terminal; and (iii) turn off control winding means associated with said high permeability core.